At the present time, most electrical power is generated and distributed as alternating current (AC) power for reasons of convenience and economy since AC power can be distributed at high voltage to reduce current and losses over power lines of reduced cost and the voltage locally reduced by transformers even though most electrical and electronic devices other than motors operate from a relatively constant voltage referred to as direct current (DC) which can be produced from an AC power source through use of simple rectifier devices or arrangements. Recently, however, there has been increased interest in substantially local generation of power from so-called renewable resources such as solar collectors and wind turbines that generally are arranged to produce DC power at a relatively high voltage which can be efficiently distributed and/or stored locally to the point of power generation; requiring the voltage to be reduced and usually regulated within a small voltage tolerance for operation of many electronic devices through use of DC-DC converters.
While many designs and approaches to DC-DC conversion have become known and accommodate the power requirements of various electronic devices relatively well, there is an increasing need for extremely rapid response to changes in the electrical load presented by the device to which power is being supplied. For example, digital data processing devices have become ubiquitous in many electrical and electronic devices to increase functionality and ease of use but present loads which can vary from very low currents in a stand-by or so-called “sleep” state to currents of many Amperes when operating at full clock cycle speeds which have greatly increased in recent years. The problem of rapid transient response has proven to be largely intractable, particularly in switching power converters and regulators which, in addition to delays in signal propagation time to alter switching parameters, require several switching cycle periods to make large step-up or step-down changes in steady-state current. Therefore, the change in load current occurs in increments to reach an increased steady-state current which cannot be optimally rapid since each switching cycle will include some finite period when the input power is interrupted.
While some approaches have been proposed to improve transient response of DC-DC power converters for step-up load transients, none have been effective of improving load transient response for step-down transients or even affecting step-down load transient response at all due to the nature of a step-down load transient, itself, which can cause excess charge to be delivered to a filter/output capacitor and output voltage overshoot even though the switching cycle is completely interrupted and no power is being delivered from the input power supply. In such cases, voltage regulation is lost and can be large enough to cause malfunction of or damage to a load, particularly if the load is a digital processing or storage device.